Simulation of the A–X and B–X transition emission spectra of the InBr molecule for diagnostics in low-pressure plasmas

Abstract

Inductively coupled low pressure discharges containing InBr have been investigated spectroscopically. In order to obtain plasma parameters such as the vibrational and rotational temperature of the InBr molecule, the emission spectra of the A 3 Π 0 + → X 1 Σ + 0 and the B 3 Π 1 → X 1 Σ + 0 transitions have been simulated. The program is based on the molecular constants and takes into account vibrational states up to v = 24. The required Franck-Condon factors and vibrationally resolved transition probabilities have been computed solving the Schrödinger equation using the Born-Oppenheimer approximation. The ground state density of the InBr molecule in the plasma has been determined from absorption spectra using effective transition probabilities for the A − X and B − X transition according to the vibrational population. The obtained densities agree well with densities derived from an Arrhenius type vapour pressure equation.

Gas temperature determination from rotational lines in non-equilibrium plasmas: a review

“…There exist many other transitions which are reported in the literature for different plasmas used for specific applications, for example [38,[201][202][203][204][205][206][207]; however, a complete overview is outside the scope of this review.…”

Diagnostics of low-pressure discharges containing InBr studied for lighting applications

“…This is the case for indium and InBr where the following transitions are utilized: 5 2 P 1/2 (GS) → 6 2 S 1/2 (indium, located at 410.2 nm) and X 1 + (GS) → A 3 0 + , B 3 1 (InBr, both located between 350 and 400 nm). For InBr, a particular absorption signal has to be assigned to the appropriate transition as described in [3] due to the overlap of the two electronic transitions, and effective transition probabilities have to be used for data evaluation [3]. For argon, a determination of the ground state density is not possible as the resonant transitions are located in the vacuum ultraviolet spectral range but it can be calculated after the ideal gas law and the filling pressure of the discharge vessel.…”

“…A promising candidate is indium bromide, which is discussed as an efficient radiator in low-pressure discharges among other diatomic molecules [1]. Using InBr, the near-ultraviolet (UV) radiation from the A 3 0 + → X 1 + and B 3 1 → X 1 + transitions (both located between 350 and 400 nm) and the intense indium lines at 410.2 and 451.1 nm can be utilized for general lighting purposes by applying a phosphor film as a converter to visible light. Investigations in capacitively coupled plasmas operated at very low discharge power already proved that high overall efficiencies of more than 40% can be achieved [2].…”

“…The results of this model are verified by applying the approved collisional-radiative model Yacora argon (see section 3.3). The population of the rovibrational states of the InBr molecule can be determined via a simulation of the relative intensity of the band emission [3]. In contrast to the simulation described in [3], the calculation method is modified in order to include both electron and heavy particle impact excitation of the vibrational states.…”

“…The population of the rovibrational states of the InBr molecule can be determined via a simulation of the relative intensity of the band emission [3]. In contrast to the simulation described in [3], the calculation method is modified in order to include both electron and heavy particle impact excitation of the vibrational states. An explanation of the modified simulation can be found in section 3.4.…”